In general, the electric power converter includes an inverter circuit that receives DC power and generates AC power, and a control circuit that controls the inverter circuit. Recently, miniaturization of the electric power converter has been demanded. Particularly, in fields of the hybrid car or the electric vehicle, it is desirable for the electric power converter to be mounted in a space as small as possible on the outside of a vehicle room, particularly, in an engine room, and additional miniaturization is demanded to improve mountability on the vehicle.
In addition, an operating hour or operating conditions (high output torque conditions) of a motor that is used as a driving source tend to increase. Therefore, in a bus bar that electrically connects a smoothing capacitor and a power module, there is a problem of reduction of heat generation which is caused by an increase in a current density due to miniaturization, and an increase in loss due to large current.
An effect of reducing a thermal effect of a bus bar on a smoothing capacitor in which a maximum using temperature is limited is described in PTL 1. However, an additional cooling countermeasure is necessary due to acceleration of an increase in a current density and a large current.